In a show of force, Syria began large-scale military exercises Sunday to simulate defending the country against outside "aggression." Damascus' staunch ally Iran warned of a "catastrophe" in the region if no political solution to the 16-month-old Syrian conflict is found.

Iran is Syria's closest ally, and has stood by President Bashar al-Assad's regime throughout the revolt against his rule despite a growing chorus of international condemnation. The relentless bloodshed has accelerated diplomatic efforts to find a solution to the crisis, and spurred some in the Syrian opposition to urge the West to intervene militarily to stop a conflict that activists say has left more than 14,000 people dead.

Iran's Deputy Foreign Minister, Hossein Amir Abdollahian, dismissed talk of foreign intervention, saying, "Nobody can imagine a military attack against Syria. We believe it will not happen. If it happens, Syria will defend itself and will not need help from Iran."

U.N. special envoy Kofi Annan, who is the architect of an international plan to end the crisis, acknowledged in an interview published Saturday that the international community's efforts to find a political solution to the escalating violence in Syria have failed. Annan arrived in the Syrian capital Sunday for talks with Assad, his spokesman Ahmad Fawzi said.

The West is reluctant to intervene in Syria in part because unlike the military intervention that helped bring down Moammar Gadhafi in Libya, the Syrian conflict has the potential to escalate quickly. Damascus has a web of allegiances to powerful forces including Shiite powerhouse Iran and Lebanon's Hezbollah, and there are concerns that a military campaign could pull them into a wider conflagration.

"Some tried to portray the Syrian president as just another aggressor. Some tried to impose a no-fly zone. We must say that Syria is different from Libya," Abdollahian said. He declined to elaborate, but added: "There will be a catastrophe in the region if there's no political solution there."

Any outside intervention would also likely face strong opposition from Syrian ally Russia, as well as China, who have already shielded Damascus from diplomatic efforts to pressure the regime.

Speaking to reporters in Amman, Jordan, Abdollahian dismissed questions about whether Iran would host Assad if he were to leave Syria, saying the issue of Assad fleeing his country and seeking refuge elsewhere was "a joke."

"He is following up on the situation in Syria. The Syrian people will decide their fate until another president is elected in 2014," he said.

Assad said in comments published Sunday that he would not step down "in the face of national challenges." He spoke in a television interview with German public broadcaster ARD, which released his comments translated into German on Sunday ahead of the full interview's broadcasting.

Assad also accused the U.S. of fueling the revolt against him by partnering with "terrorists ... with weapons, money or public and political support at the United Nations."

The regime frequently uses the term "terrorists" to refer to Syrians seeking to topple Assad.

The Syrian military maneuvers began Saturday with naval forces repelling a simulated attack from the sea, and will include air and ground forces over the next few days, the state-run SANA news agency said. State TV broadcast footage of missiles being fired from launch vehicles and warships — an apparent warning to other countries not to intervene in the country's crisis.

Syrian Defense Minister Dawood Rajiha attended the maneuvers and praised the "exceptional performance" of the naval forces, saying they showed "a high level of combat training and ability to defend Syria's shores against any possible aggression."

"The navy carried out the training successfully, repelling the hypothetical attack and striking at given targets with high precision," the report said.

The maneuvers are the second to be carried out by the Syrian military since the uprising began 16 months ago.

Annan said Saturday that the international community's efforts to find a political solution to the escalating violence in Syria have failed.

"The evidence shows that we have not succeeded," he told the French daily Le Monde.

Annan, the special envoy for the U.N. and the Arab League, is the architect of the most prominent international plan to end the crisis in Syria.

His six-point plan was to begin with a cease-fire in mid-April between government forces and rebels seeking to topple Assad. But the truce never took hold, and now the almost 300 U.N. observers sent to monitor the cease-fire are confined to their hotels because of the escalating violence.

U.S. Secretary of State Hillary Rodham Clinton said Sunday that time was running out on Syrian peace hopes and warned that the Syrian state could collapse.

Speaking in Japan, Clinton said Annan's acknowledgment that his peace plan was failing "should be a wake-up call for everyone."

She said last month was the deadliest for the Syrian people since the revolt began in March 2011, but added that the opposition "is getting more effective in defense of themselves and going on the offensive against the Syrian military."